Resonant single-photon
transitions are ubiquitous in nature and have fundamental important to
physics and technology. This includes recent areas of study, such as
adiabatic population transfer, electromagnetically induced transparency,
cooling and trapping of atoms, slowing and stopping of light, and quantum
information. Early work in strong field physics suggested that single
photon processes could be extended to multiple photons, with a
corresponding increase in the scale of excitation. If so, innershell
ionization, multiply excited states, X-ray transitions and X-ray lasers
could be accessed through multiphoton transitions with optical or near-UV
lasers. In this talk, I will give a general introduction to the behavior
of atoms and molecules in high-intensity laser fields, but then focus on a
very simple question: under what conditions (if any) is it possible to
drive a resonant 20-photon bound-bound transition?